Dear student,

For solutions, concentration term normality (N) is used, which can be defined as " the number of equivalent of solute present in one litre (1000mL) solution ".

Now,

N = (number of gram equivalents of solute) / (volume of solution in litre)

Therefore,

N = ( weight (in gm) × 1000 ) / (E × V (inml) )

Where, E = equivalent weight = molar mass / n factor

And therefore, N = (MOLARITY) × ( n factor)

So, as the given concentration is 0.45N HCl , therefore the molarity (M) = NORMALITY / n factor

n factor of HCl = 1

So, Molarity of 0.45N HCl = 0.45/1 = 0.45 M